Oil vapor extraction system

ABSTRACT

A method for removing hydrocarbons from a stream of compressed air for use in a compressed air supply and delivery system of the type wherein a supply of compressed air is provided by a lubricated or non-lubricated air compressor includes the passing of the compressed air from the lubricated air compressor through a catalytic oxidation system to remove hydrocarbons, including vapor phase hydrocarbons, from the compressed air stream. The method contemplates feeding the stream of compressed air from an outlet of the air compressor to a treatment station, which treatment station utilizes a catalytic oxidation system to remove the hydrocarbons from the compressed air stream, thereby oxidizing the hydrocarbons into carbon dioxide and water and removing a predetermined, relatively high percentage of existing hydrocarbons from the compressed air stream prior to reaching downstream portions of the delivery system and any connected utilization apparatus. A compressed air system in which the foregoing method is carried out also forms a part of the invention. The invention also extends to a catalytic oxidation system for use in removing hydrocarbons, including vapor phase hydrocarbons, from a compressed air stream.

This application is a continuation-in-part, of application Ser. No.408,439, filed Sep. 15, 1989 abandoned, which is a continuation-in-partof application Ser. No. 07/223/706, filed Jul. 22, 1988, abandoned,which is a continuation of application Ser. No. 07/026,955, filed Mar.17, 1987, abandoned, which is a divisional of application Ser. No.06/857,712, filed Apr. 30, 1986, abandoned.

BACKGROUND OF THE INVENTION

The invention concerns a novel method and apparatus for the removal ofhydrocarbons from a compressed air/gas stream. Specifically, theinvention utilizes a catalytic oxidation method and system to removehydrocarbons from compressed air.

Compressed air and/or gas has a wide variety of industrial uses. Forexample, compressed air or gas may be utilized to transmit power, suchas in a system for operating pneumatic tools. Alternatively, compressorsare often utilized to provide air for combustion in various apparatus.Compressed air may also be utilized to transport and distributematerial, such as in air conveying. Compressed air is also used ininstrumentation systems throughout industry. Other uses for compressedair or gas include producing or creating conditions more conducive tocertain chemical reactions or processes, as well as producing andmaintaining desired pressure levels for many purposes. Such uses mayrequire the removal of contaminants which have either leaked or flowedinto the system, or are initially present, although unwanted.

Generally speaking, compressed air or gas may be generated by eitheroil-lubricated type compressors (hereinafter "lubricated compressor(s)")or oil-free, non-lubricated type compressors. The latter oil-free ornon-lubricated type compressors are relatively expensive to manufacture,operate and maintain. In this regard, the initial cost of purchasing orproviding such a non-lubricated compressor is higher than a comparableoil lubricated type compressor. Moreover, non-lubricated compressorsgenerally consume significantly greater quantities of energy inoperation, being typically from 3 percent to 15 percent less efficientthan lubricated compressors. Hence, in general, non-lubricatedcompressors cost 15 percent to 100 percent more than lubricatedcompressors to purchase initially and require about 25 percent to 50percent more maintenance. Heretofore, many industrial users have beenwilling to absorb these higher costs because of problems caused bycompressor lubricants in the less expensive lubricated type ofcompressors.

In this latter regard, while oil-lubricated compressors are more energyefficient, cost significantly less to purchase and require lessmaintenance than non-lubricated compressors, lubricating oil carry-over(hydrocarbons) in the downstream compressed air causes a number ofproblems in practice.

Due to the relatively high temperatures and pressures utilized in theair compression process, the lubricants in the downstream air undergoseveral changes. The oils have in effect been fractionated and crackedand have lost, or been greatly reduced in, their lubricating properties.These oils or hydrocarbons often further mix with water and/or solidparticulate matter or "dirt" present in the air/gas stream which maycause severe damage to downstream components. Such problems may includewashing away of lubricants required on the downstream instruments ormachinery resulting in increased wear and increased required maintenancethereof. This combination of oil, dirt and water in the downstream aircan also cause automatic valves, cylinders and like equipment to operateeither slowly, unreliably or not at all, as well as causing malfunctionsof instrumentation in the air/gas stream. In some systems, productspoilage is caused by these unwanted contaminants, and excessive rustand/or abrasion of downstream parts or products may occur. It has alsobeen found that these contaminants in the air/gas stream can causeoutdoor air lines to freeze in cold weather.

Additionally, in an air compressor system, oxygen is always present, andwhere petroleum oils are used as a lubricant, there must be some concernfor the potential of fire or explosion in the system. A source of energyfor ignition may be provided by friction, static electricity or heatfrom the compressor, often in the form of hot carbon particles in theair/gas stream. Most commonly, the petroleum oils used as a lubricant,and present to some degree in the air/gas stream, decompose to form suchcarbon particles. These particles form deposits which tend to collect onthe valves, heads, discharge ports, and in piping in delivery andutilization systems. Tests have shown that such carbon deposits absorboxygen from the air and under certain conditions generate heat. Thisheat may reach a point where ignition occurs in the carbon deposits, andsuch ignition may cause further fire or explosion elsewhere in thesystem, as well.

Moreover, many treatment systems include drying devices for removingmoisture from the compressed air. These drying devices generally work byheating the compressed air, which is often initially at a relativelyelevated temperature from compression. In the presence of suchrelatively elevated temperatures and heating devices, the presence ofhydrocarbons in the system can pose a danger of fire or explosion. Thatis, the hydrocarbon based compressor lubricant lost through bypass orthermal cracking is often transmitted into the compressed air, and theresulting hydrocarbons contaminate treatment and/or distribution systemsdownstream, often becoming trapped in treatment sections where theysometimes ignite or detonate. In this regard, conventional treatmentsections often include mechanical oil filtering devices. While oil andcracked oil products are always present as low concentrationcontaminants in lubricated systems, concentration can rise over longperiods of operation to a point where serious problems are caused orthreatened. Such problems are particularly acute for drying systemswhich operate at elevated temperatures and therefore can more easilycause ignition in the presence of excess hydrocarbons.

A number of lubricants are utilized in air compressors, refinedpetroleum products being the most prevalent. Synthetic type lubricantsare also utilized, and these latter materials are believed to provide alesser danger of fire or explosion in a system. However, volatilepyrolysis products are often produced for such synthetics in the systemwhich can still cause a danger of fire or explosion. Syntheticlubricants have other disadvantages as well. Due to the energy intensivemanufacturing processes utilized in their production, syntheticlubricants are from five to seven times as expensive as petroleum basedlubricants. Additionally, most synthetic lubricants tend to exhibitrelatively low viscosity, causing low temperature handling problems.Moreover, many commonly used gasket, seal packing and lubricatormaterials are attacked by synthetic lubricants.

In addition to the foregoing, one particularly advantageous type ofdryer, known as a regenerative heat of compression drying systemgenerally cannot be utilized with lubricated compressors. Such heat ofcompression drying systems generally reuse the heat energy generatedduring the compression process which is otherwise lost as waste heatenergy. Hence, such heat of compression type dryers are relativelyinexpensive to operate. Since they utilize a source of energy alreadypresent in the system, such dryers virtually eliminate the conventionalenergy costs of drying air. However, these energy efficient heat ofcompression drying systems operate at elevated temperatures such thatthey are normally ruled out for use in connection with lubricated typecompressors. That is, because of the presence of hydrocarbons in thedownstream flow from such lubricated compressors, the relatively hightemperature of operation of heat of compression drying systems isgenerally believed to pose too great a threat of auto ignition tojustify their use.

While, as mentioned above, mechanical filters have been utilized in aneffort to remove hydrocarbons from the compressed air stream fromlubricated compressors, such mechanical filtering is of limitedusefulness. For example, a typical filter operates in liquid phase andhence can only remove hydrocarbons in liquid phase from the air stream.However, since the air is generally at an elevated temperature leavingthe compressor and can approach saturation with oil vapor, hydrocarbonsor oil products still in vapor form will pass through the filter, and asthe air cools downstream of the filter, will condense into the liquidstate.

Moreover, conventional filters require daily draining and periodicreplacement of filter cartridges, in the absence of which they rapidlybecome ineffective. Such maintenance procedures are of course relativelytime consuming and expensive and can require system shutdown to carryout. However, as mentioned above, even properly maintained filters cancollect a quantity of hydrocarbons over a period of operation, thusposing potential ignition or detonation dangers in the presence of theelevated temperatures of the compressed air and gases in the system.

The development of hydrocarbon catalysis coincides with the arrival ofthe petroleum age, when natural oil and gas provide most of our energyand an increasing share of raw materials for chemical industry.According to the well known principles of catalytic action, unstablespecies may result when a hydrocarbon molecule collides with the activecenter of a catalyst. The nature and reactivity of these intermediatesdetermine the products of catalysis and the rate of reaction.

Vapor phase catalytic oxidation and reduction is used for the removal ofa large variety of objectionable compounds from many types of gasstreams. Catalytic oxidation is particularly suitable for removing smallamounts of combustable contaminants from gas streams containing thesecompounds in concentrations below the flammable limit, and, therefore,has found wide application in the field of air pollution and odorcontrol. Similar applications include automobile exhaust catalyticconverters and carbon monoxide converters for breathing air inindustrial compressed air systems. The catalytic oxidation apparatus andsystem for removal of hydrocarbons from compressed air/gas differs fromthese similar systems in several significant ways. Automotive exhaustsystems are designed to remove trace amounts of hydrocarbons fromatmospheric pressure emmission systems operated at extremely hightemperatures for the protection of the environment. Carbon monoxideconverters are used in industrial applications for the conversion ofcarbon monoxide, a potentially deadly contaminant, into harmless carbondioxide when used in breathing air apparatus.

None of the catalysts utilized in these related applications wouldperform when tested in the catalytic oxidation system for removal ofhydrocarbons in compressed air. The basic design considerations of thecatalytic oxidation system preclude utilization of existing technologyand in fact required the development of new catalysts and technology.

OBJECTS OF THE INVENTION

Accordingly it is a general object of the invention to provide a noveland improved method and apparatus for removing hydrocarbons fromcompressed air.

A more specific object is to provide a method and apparatus for removinghydrocarbons from compressed air which substantially overcomes theabove-discussed problems.

A related object is to provide a method and apparatus in accordance withthe foregoing objects which may be utilized in a system including aregenerative, heat of compression type drying apparatus.

A further related object is to provide a hydrocarbon removal apparatusand method in accordance with the foregoing objects which is relativelysimple and inexpensive in its design, construction and operation andrequires but minimal maintenance, and yet is highly reliable inoperation.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the present invention which are believed to be novel areset forth with particularity in the appended claims. The organizationand manner of operation of the invention, together with further objectsand advantages thereof, may best be understood by reference to thefollowing description taken in connection with the accompanying drawingsin the several figures of which like reference numerals identify likeelements, and in which:

FIG. 1 is a somewhat diagrammatic representation of an air compressorsystem provided with a hydrocarbon removal system in accordance with themethod and apparatus of the invention;

FIG. 2 is an enlarged axial section of the catalytic oxidation system ofFIG. 1;

FIG. 3 is a top plan view taken generally in the plane of the line 3--3of FIG. 2;

FIG. 4 is an enlarged axial section similar to FIG. 2 of a catalyticoxidation system in accordance with a second embodiment of theinvention; and

FIG. 5 is a somewhat diagrammatic representation of an air compressorsystem utilizing a pair of catalytic oxidation systems in accordancewith the embodiment of FIG. 4.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

The method and apparatus of the invention will be discussed hereinbelowwith reference to the specific features of the illustrated embodiment.However, it should be understood that the invention is not limited tosuch specific features or to the illustrated embodiments but includessuch modifications, alternatives and changes as may become apparent tothose skilled in the art upon reading the foregoing discussion andfollowing description and considering the accompanying drawings.Accordingly, it is intended that the invention include suchmodifications, alternatives and changes insofar as they fall within thespirit and scope of the appended claims.

Referring now to the drawings, the method of the invention willinitially be described in connection with the apparatus diagrammaticallyillustrated in FIG. 1. In accordance with the invention, there isprovided a method for removing hydrocarbons from a stream of compressedair for use in a compressed air supply and delivery system of the typewherein a supply of compressed air is provided by an air compressor 10which may be either a lubricated or a non-lubricated air compressor.Generally speaking, such a compressor has an air intake or inlet portion12 which is often provided with a suitable intake filter 14. Compressedair produced by the compressor 10 is then delivered through a dischargeoutlet 16 to downstream delivery systems and/or utilization apparatus(not shown).

In accordance with the method of the invention, the stream of compressedair is fed from the outlet 16 of the air compressor 10 to a treatmentstation designated generally by reference numeral 18. Further inaccordance with the invention, at this treatment station 18 thecompressed air is treated by being passed through a catalytic oxidationapparatus or system to remove hydrocarbons including vapor phasehydrocarbons from the compressed air stream. In this regard, thetreatment station 18 includes a catalytic oxidation apparatus designatedgenerally by the reference numeral 20 which is utilized to oxidizehydrocarbons in the incoming compressed air stream into harmless carbondioxide and water vapor to thereby remove a relatively high percentageof pre-existing hydrocarbons from the incoming compressed air stream.Hence, the catalytic oxidation system 20 provides treated, substantiallyhydrocarbon-free, compressed air for delivery to the downstream deliverysystem and utilization apparatus.

In accordance with a preferred form of the invention, this method andapparatus or system further includes drying of the compressed air,preferably utilizing a regenerative, heat of compression type of dryingsystem or apparatus designated diagrammatically at reference numeral 22.This regenerative type of drying apparatus preferably comprises the typeof drying system shown and described in U.S. Pat. No. 3,950,154 issuedApr. 13, 1976, to Terry Henderson. Advantageously, such a heat ofcompression drying system obtains the necessary heat energy for itsoperation from the heat of compression generated in the compressor 10.Accordingly, this otherwise wasted heat energy can advantageously beutilized as a relatively low-cost source of heat for the regenerativedrying system 22.

As more fully described in the above-referenced U.S. patent, the system22 operates in part by bypassing and heating some of the air in thesystem to regenerate the desiccant material utilized in drying. Hencethe heating of this air utilizing the heat of compression fromcompressor 10 advantageously provides the necessary heat energy at verylittle additional cost.

Referring now to Figs. 2 and 3, the catalytic oxidation system 20comprises a vessel 25, here shown in axial section, which includes aninlet air connection 30 and an outlet air connection 32. Both of theseair connections are provided with suitable fittings 35 as illustrated inFIG. 3 for coupling the same in series with the outlet 16 of thecompressor, and with downstream distribution and utilization equipmentwhich may include the dryer system 22 as illustrated in Fig. 1.Interiorally of the vessel 25 a quantity of a catalyst material 34 ismaintained between respective inlet and outlet catalyst retainer screens36 and 38. Preferably, the inlet and outlet catalyst retainer screensare sufficiently fine to retain the catalyst material therebetween whileallowing the free passage of air therethrough. Hence, the vessel 25 andscreens 36 and 38 define a generally tubular chamber 40 filled with aquantity of a predetermined catalyst material 34.

This catalyst material 34 may comprise pelleted or pelletized materialor a porous, solid monolith material. Moreover, different catalysts maybe utilized without departing from the invention. In this regard, theform and identity of catalysts utilized may be determined by therequirements of a given system. Such factors as the desired percentageof hydrocarbon removal, as well as the useful service life of a givencatalyst and its capacity for hydrocarbon removal to the desiredpercentage with a given flow rate of air all must be taken intoconsideration. Moreover, in order to provide a commercially attractiveunit, the ratio of the cost of catalyst per unit weight as against itscapacity for treatment at a given flow rate of air must be taken intoconsideration. Accordingly, it will be recognized that differentcatalysts may be useful and economically feasible, given therequirements of a particular system.

An important feature of the method and system of the invention, is itsability to successfully oxidize and remove oil vapor at a surprisinglylow temperature relative to previously known systems and methods. Forexample, the system taught by U.K. patent No. GB 1,103,693 specificallyrequires relatively high temperatures on the order of between 500° C. to600° C. to effect the oxidation. This patent does not contemplate usefultemperatures below about 350° C. in any event, and contemplates thatcontinuous heat must be added to the system at all times to bring thecatalyst temperature up to the required operating range. Similarly,automotive catalysts which conduct a similar type of oxidation alsooperate at a similar temperature range.

Departing from the conventional practice, we have found that the use ofa sufficiently active catalyst (a "high-activity" catalyst) will permitoxidation to occur at temperatures below 500° F. (260° C.). Accordingly,the method and system of the invention operate at a relatively lowreaction temperature which may, in many cases, be supplied by thecompressor heat already present in the system. Even in compressed airsystems not operating at a sufficiently high temperature, our novelsystem and method permits great savings in energy consumption sinceconsiderably less heat energy must be added than that called for, forexample, in the above-mentioned U.K. patent.

We have found that one particularly useful high-activity catalystmeeting the above low-temperature oxidation criteria comprises analuminum oxide pellet substrate which is coated with substantially onepercent platinum by weight. Alternatively stated, the platinum contentis preferably in the range of from substantially 50 to 200 grams andmore preferably still on the order of substantially 100 grams ofplatinum per cubic foot of substrate. Such a material may b obtainedfrom ASACC Industrial Catalyst, Allied Signal Inc., Tulsa, Okla. AlliedSignal produces catalyst materials of this general type by a proprietaryprocess, which process and the class of catalyst materials producedthereby are identified as Allied Signal's PURZAUST® oil mist oxidationcatalyst. In order to obtain a specific catalyst made by this process,it is necessary to specify the particular requirements and desired usesof the catalyst, for example, as has been done hereinabove.

We have found that good results can be obtained with an 0.5 percent orgreater and preferably a commercial two-percent platinum catalystmaterial (i.e., a catalyst material having a platinum content of on theorder of 0.5 percent or greater by weight, and preferably 2 percent byweight) on a carrier or substrate of spherical pelletized aluminamaterial. However, it may be reasonably expected that similarperformance may be obtained from catalysts utilizing little or none ofthis relatively expensive platinum material. Also, different substratesor carriers may be utilized. Moreover, in selecting a catalyst, at leasttwo design parameters based upon two types of lubricated compressorsmust be taken into consideration.

The first design parameters are based on lubricated reciprocating typecompressors. In such compressors, oil carry-over may vary from between 5and 100 ppm by weight. The typical discharge temperatures of suchcompressors vary from 250 degrees F. to 350 degrees F. Typicallubricating oils are SAE 30 and SAE 40 weight, both detergent andnon-detergent. A second type, lubricated rotary screw-type compressors,normally operate at temperatures ranging from 100 degrees F. to 200degrees F. These compressors often use lighter weight oils aslubricants.

Typically, the air pressure entering the catalytic oxidation 20 will beon the order of 100 PSIG, although it can be much lower or much higher.Optimally, the selection of the catalyst and design of the screens 36and 38 will be such that the pressure drop across the inlet and outlet30, 32 is no greater than on the order of 2 PSIG. In addition to theabove-described catalyst, the catalyst utilized in the oxidation systemmay comprise one or more of the following material: platinum, palladium,nickel, cobalt, iron, rhodium, manganese, copper, on a substrate orcarrier comprising alumina or silica or crystalline aluminosilicates orzeolites having a surface area greater than 20 m² /g, suitable poresize, suitable pore volume and resistance to mechanical and chemicalfatigue.

Referring now also to FIGS. 4 and 5, there is illustrated a furtherembodiment of a catalytic oxidation system (FIG. 4) and an aircompressor arrangement (FIG. 5) using two catalytic oxidation apparatusof the type shown in FIG. 4. Referring intitially to FIG. 4, a catalyticoxidation apparatus 20a is similar in many respects to the catalyticoxidation apparatus illustrated and described in FIGS. 2 and 3.Accordingly, like elements have been designated by like referencenumerals with the suffix a. However, in addition to the structures shownin FIG. 2, the apparatus of FIG. 4 also includes at least one additionalheater or heating means 42 which, in the illustrated embodiment,preferably comprises an electric heater of the cartridge type having atungsten filament 44 or any other suitable electrical resistance heatingelement.

In addition to the heater 42, or in place thereof, there is illustrateda spark plug 46 or other similar energy adding device. One or both ofthese heaters or energy adding elements are utilized for the purpose ofraising the temperature of the compressed air and/or compressor oilcarried therein, and/or the catalyst 34a to better facilitate thecomplete catalytic conversion of the compressor lubricating oil whichmay be carried in the air stream into carbon dioxide and water vapor bythe catalyst 34a.

It should be understood in this regard that some improvement in theperformance of the system may be realized by the use of a catalystmaterial containing a higher proportion of noble metal. This alsorenders the apparatus of the invention quite expensive in practice.However, we have found that the performance of the system may beenhanced without the use of a noble metal catalyst (i.e., aplatinum-base catalyst) by raising the temperature of operation of thecatalyst in the chamber 40. Thus a somewhat less reactive catalyst usingless or, perhaps, no noble metal may operate satisfactorily byincreasing the operating temperature.

It will be further understood in this regard that the temperature of thecompressed air entering the apparatus may be on the order of 250° F. to350° F., as mentioned above or, alternatively, with some types ofcompressors as low as 100° F. to 200° F., as also mentioned above. Inorder to obtain improved catalytic action, we propose adding a heatingmeans either in the form of a heating element or heater 42 and/or aspark plug or similar element 46.

In accordance with yet a further aspect of the invention, in the case ofa compressed air system in which a continuous supply of air is notnecessary, a single catalytic oxidation element may be used as in FIG.4, We further propose in such a system to utilize suitable controlmeans, diagrammatically indicated at reference numeral 50 in FIG. 4, forcontrolling the air flow through the apparatus 20a. In this regard, wepropose utilizing or operating the apparatus 20a essentially on anintermittent basis, whereby the heat generated by the exothermicreaction with the catalyst is retained within the housing 25a. When thecontrol 50 is activated to stop the air flow to the housing 25a, thisheat will be retained and will build up within the housing 25a, therebyenhancing the catalytic reaction and removing the greater proportion orpercentage of the compressor oil from the air within the catalystchamber 40a. That is, with no air flow to carry away the heat generatedin the process, the catalyst temperature should rise, further enhancingthe catalyst performance. Moreover, during this offstream or no-flowperiod, much less energy would be necessary to sufficiently heat thecatalyst by either the heater 42 and/or spark plug 46, such that thesemight also be de-energized by the control means or system 50 during thistime.

It should further be recognized that in a typical compressed air systemit is important to control the temperature of the air passing from theoutlet of the apparatus 20 or 20a in order to avoid damage to downstreamcompressor system components such as various valves, seals and the likewhich are designed for operating temperatures on the order of the100°-350° F. ranges mentioned above. Hence it is important to shut downthe air flow at control 50 in the event the temperature achieved by theheater and/or spark plug, exceed the allowable limits of thesedownstream components. Of course, during no-flow or offstream time, theelevated temperatures will be essentially experienced only withinapparatus 20a and air at such elevated temperature will not reachdownstream components.

Turning now to FIG. 5, in many operational situations, it is notdesirable or practical to shut down the compressed air flow through thesystem. Accordingly, we propose to use at least two substantiallyidentical catalytic oxidation units such as unit 20a shown at FIG. 4. Asuitable control system, diagrammatically illustrated in FIG. 5, isutilized to intermittently switch the air flow from one of the catalyticoxidation units 20a to the other, so as to allow some period ofoffstream or no-flow condition for each unit for the improved catalyticaction as described above with reference to the apparatus of FIG. 4.That is, the above-described offstream or no-flow period can be utilizedwith or without activation or de-activation of the heater and/or sparkplug elements by use of appropriate control devices, including timers,valves, and the like as diagrammatically illustrated in FIG. 5.

Briefly, FIG. 5 illustrates an additional and optional prefilter 52which may isolate and remove some of the compressor oil from thecompressed airstream. A flow regulating valve 53 may be connected inline following the prefilter 52 and in turn feeds a first or "inlet"three-way valve 54. The three-way valve 54 has its alternativelyselectable outlet ports connected to respective inlets 32a and 32a' ofthe respective catalytic oxidation systems or apparatus 20a and 20a'respectively. A similar "outlet" three-way valve 56 is similarly coupledto the respective outlets 30a and 30a' of the two catalytic oxidationunits. The outlet three-way valve 56 is connected to the instrument airoutlet, which may be further directed initially to a desiccant or dryingsystem 22, as mentioned hereinabove with respect to FIG. 1.

A suitable control for the respective three-way valves 54 and 56 maytake the form of a cylinder-type of valve actuator 58, which is in turncontrolled in its operation by a suitable control device 60. The controldevice 60 may comprise a timer for switching between the two units 20aand 20a' on a preset or preselectable timed basis, or may comprise asuitable condition sensor, such as means for sensing the oil content orsome other suitable indicator of system operation for purposes ofswitching between the respective units 20a and 20a' in an appropriatemanner.

The heating of the catalyst may also be accomplished by utilizing theheat of compression obtained rom the compressor without departing fromthe invention.

While particular embodiments of the invention have been shown anddescribed in detail, it will be obvious to those skilled in the art thatchanges and modifications of the present invention, in its variousaspects, may be made without departing from the invention in its broaderaspects, some of which changes and modifications being matters ofroutine engineering or design, and others being apparent only afterstudy. As such, the scope of the invention should not be limited by theparticular embodiment and specific construction described herein butshould be defined by the appended claims and equivalents thereof.Accordingly, the aim in the appended claims is to cover all such changesand modifications as fall within the true spirit and scope of theinvention.

The invention is claimed as follows:
 1. A compressed air systemcomprising in combination: an air compressor having a compressed airoutlet wherein compressed air is discharged to a delivery system coupledto downstream utilization apparatus; and a catalytic oxidation systemhaving an inlet coupled to said compressor outlet to receive saidcompressed air therefrom, and comprising a treatment chamber containinga quantity of a catalytic oxidizing material for oxidizing compressoroil carried in the compressed air into carbon dioxide and water tothereby form treated compressed air having a predetermined percentage ofpre-existing compressor oil removed therefrom, an outlet coupled withsaid delivery system for delivering said treated compressed airtherethrough to said downstream utilization apparatus; and control meansfor periodically stopping the air flow to said catalytic oxidationsystem for allowing further heat buildup therein to further enhance thecatalytic reaction therein; wherein said catalytic oxidizing materialcomprises a high-activity catalyst effective at an operating temperaturebelow about 500° F. (260° C.).
 2. A system according to claim 1 in whichsaid catalyst comprises a concentration in the range of from 50 grams to200 grams of platinum per cubic foot an a substrate of pelletizedaluminum oxide.
 3. A system according to claim 1 and further includingdryer means interposed in series with said compressed air discharge andsaid catalytic oxidation system for drying said compressed air.
 4. Asystem according to claim 3 wherein said dryer means comprises a heat ofcompression-type regenerative dryer for using heat of compressiongenerated by said air compressor as a source of heat energy for theregenerative drying of the compressed air discharged therefrom.
 5. Asystem according to claim 1 wherein said catalytic oxidation systemcomprises a generally tubular chamber containing a quantity of apredetermined catalyst.
 6. A system according to claim 5 wherein saidcatalyst comprises one or more of platinum, palladium, nickel, cobalt,iron, rhodium, manganese, and copper, on a substrate comprising aluminaor silica or crystalline aluminosilicates or zeolites having a surfacearea greater than 20 m² /g, a predetermined pore size, a predeterminedpore volume and resistance to mechanical and chemical fatigue.
 7. Asystem according to claim 5 wherein said predetermined catalystcomprises a 0.5 percent or greater concentration of platinum, by weight,on a substrate.
 8. A system according to claim 1 wherein said catalyticoxidation system further comprises a generally tubular vessel defining achamber, an inlet catalyst retainer screen extending transversely acrosssaid chamber at a first, inlet side thereof; an outlet catalyst retainerscreen extending transversely across said chamber at a second, outletside thereof; and a quantity of catalyst substantially filling saidchamber intermediate said inlet and outlet catalyst retainer screens. 9.A system according to claim 8 wherein said catalytic oxidation systemfurther comprises an air inlet connection coupled with said inlet sideof said chamber and an air outlet connection coupled with said outletside of said chamber.
 10. A compressed air system according to claim 1and further including a second catalytic oxidation system having aninlet coupled to said compressor outlet and an outlet coupled to saiddownstream utilization apparatus, and wherein said control means furtherincludes valve means coupled to said two catalytic oxidation systems foralternating the flow of compressed air to one or the other thereof in acontrolled, intermittent fashion, so as to permit said periodic stoppingof air flow to each said catalytic oxidation system for allowing furtherheat buildup therein to further enhance the catalytic reaction therein,while maintaining a flow of compressed air to said downstreamutilization apparatus at all times.
 11. A compressed air systemaccording to claim 1 and further including heating means in thetreatment chamber of said catalytic oxidation system.
 12. A catalyticoxidation system for removing compressor oil from a compressed airstream comprising: a generally tubular housing having an air inletconnection for coupling to a source of compressed air and an air outletconnection to be coupled to a downstream delivery system and utilizationequipment; an inlet catalyst retainer screen extending transverselyacross said chamber at a first, inlet side thereof in communication withsaid inlet air connection; an outlet catalyst retainer screen extendingtransversely across said chamber at a second, outlet side thereof incommunication with said outlet air connection and spaced apart from saidinlet catalyst retainer screen; and a quantity of predetermined catalystsubstantially filling said chamber between said inlet catalyst retainerscreen and said outlet catalyst retainer screen, and control means forperiodically stopping the air flow to said tubular housing system forallowing further heat buildup therein to further enhance the catalyticreaction therein; wherein said catalyst comprises a high-activitycatalyst effective at an operating temperature below about 500° F. (260°C.).
 13. A system according to claim 12 in which said catalyst comprisesa concentration in the range of from 50 grams to 200 grams of platinumper cubic foot on a substrate of pelletized aluminum oxide.
 14. A systemaccording to claim 12 wherein said catalyst comprises one or more ofplatinum, palladium, nickel, cobalt, iron, rhodium, manganese, andcopper, on a substrate comprising alumina or silica or crystallinealuminosilicates or zeolites having a surface area greater than 20 m²/g, a predetermined pore size, a predetermined pore volume andresistance to mechanical and chemical fatigue.
 15. A system according toclaim 12 wherein said predetermined catalyst comprises a 0.5 percent orgreater concentration of platinum, by weight, on a substrate ofspherical pelletized alumina material.
 16. A catalytic oxidation systemaccording to claim 12 and further including a second tubular housing,having a chamber filled with a quantity of said predetermined catalystand having an inlet coupled to said compressor outlet and an outletcoupled to said downstream utilization apparatus, and wherein saidcontrol means further includes means coupled to said two tubularhousings for controlling the direction of compressed air to one or theother thereof in a controlled, intermittent fashion, so as to permitsaid periodic stopping of air flow to each said catalyst-filled chamberfor allowing further heat buildup therein to further enhance thecatalytic reaction therein.
 17. A catalytic oxidation system accordingto claim 12 and further including heating means in the catalyst-filledchamber of each said tubular housing.
 18. A compressed air systemcomprising in combination: an air compressor having a compressed airoutlet wherein compressed air is discharged to a delivery system coupledto downstream utilization apparatus; and a catalytic oxidation systemhaving an inlet coupled to said compressor outlet to receive saidcompressed air therefrom, and comprising a treatment chamber containinga quantity of a high-activity catalyst for oxidizing compressor oilcarried in the compressed air into carbon dioxide and water to therebyform treated compressed air having a predetermined percentage ofpre-existing compressor oil removed therefrom, and an outlet coupledwith said delivery system for delivering said treated compressed airtherethrough to said downstream utilization apparatus; wherein saidhigh-activity catalyst comprises a catalyst effective at an operatingtemperature below about 500° F. (260° C.).
 19. A compressed air systemaccording to claim 18 in which said catalyst comprises a concentrationin the range of from 50 grams to 200 grams of platinum per cubic foot ofsubstrate of pelletized aluminum oxide.
 20. A catalytic oxidation systemfor removing compressor oil from a compressed air stream, comprising incombination: an air inlet coupled to receive said stream of compressedair, a treatment chamber containing a quantity of a high-activitycatalyst for oxidizing any compressor oil carried in the compressed airinto carbon dioxide and water to thereby form treated compressed airhaving a predetermined percentage of pre-existing compressor oil removedtherefrom, and an outlet coupled with a delivery system for deliveringsaid treated compressed air therethrough to downstream utilizationapparatus; wherein said high-activity catalyst comprises a catalysteffective at an operating temperature below about 500° F. (260° C.). 21.A compressed air system according to claim 20 in which said catalystcomprises a concentration in the range of from 50 grams to 200 grams ofplatinum per cubic foot on a substrate of pelletized aluminum oxide.